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It's a finding which will be familiar to any women used to dealing with the attentions of libidinous male gym dwellers.

Shots of testosterone cause male canaries to sing more songs in a bid to attract a female, researchers have found, suggesting that steroids may have a similar effect on human sexuality.

Scientists at the The Johns Hopkins University injected testosterone directly into the brains of canaries, to see how differing doses affected the animals’ voices.

These birds use their songs to attract female canaries. The researchers suspected testosterone played a key role in the behavior behind the singing.

The birds must be careful to sing a decent song, because the fussy females are more attracted to a male with a fine voice, rather than one which chirps tunelessly.

To carry out the experiment, a team of researchers first simulated spring time using light and heating systems, so they could observe the musical mating ritual which takes place at this time of year.

One group of male canaries were injected with testosterone in the medial preoptic nerve (PON), which controls the sex drive in a number of species - including humans. Another group had their whole brain bathed in the male hormone.

Testosterone caused both sets of birds to sing more songs, but the birds which were injected in the PON sung songs of a lower quality, while the others' tunes did not suffer. In fact, they sung rather well, suggesting that testosterone acts on several parts of the brain at once during the courtship ritual.

"Our data suggests that testosterone needs to act in different areas of the brain to regulate the specific components of this complex social phenomenon," said Beau Alward, lead author of a paper on the research.

"It appears that, like in so many other species, testosterone in the POM can regulate an animal's motivation, in this case, the motivation to sing. However, singing and courting a female is more than just motivation. There is the quality of the song that is required to successfully attract a mate and then the process of attending to the female, or singing to her, when she is there which requires the coordination of multiple brain regions."

The results could have implications for humans, particularly on the study of how steroid use affects sexual behavior.

"The hormones in these birds are identical to those in humans and they can regulate brain changes in a similar manner," said Gregory F. , vice dean for science and research infrastructure and professor in the Department of Psychological and Brain Sciences in the Zanvyl Krieger School of Arts and Sciences,

The paper is called Differential effects of global versus local testosterone on singing behavior and its underlying neural substrate and was published in the journal PNAS.